Miniaturized environments have emerged as an excellent alternative to evaluate and understand biological mechanisms. These systems are able to simulate macroenvironments with high reproducibility, achieving many results in a short time of analysis. However, microenvironments require specific architectures that can be reached using laser micromachining techniques, such as two-photon polymerization (TPP)

Graded index multimode fibre (GIMF) has emerged as a promising platform for two- and three-dimensional nonlinear optics. Based on the nonlinear multimodal interference technique, GIMF has demonstrated the saturable absorption effect and applied for fibre-based-laser short pulse generation as versatile, wideband ultrafast optical switches. Herein, this review presents the basic principles and the optical

Thin-disk lasers (TDLs) have made spectacular progress in the last decades both in continuous-wave (CW) and ultrafast operation. Nowadays, single thin-disk oscillators with >16 kW of CW-power have been demonstrated and ultrafast amplifiers have largely surpassed the kilowatt milestone with pulse energies in the multi-100 mJ range. This amazing development has been demonstrated in the 1 m wavelength

Dielectric microelements with circular symmetry have shown interesting optical properties: photonic nanojets (PNJs) and whispering gallery modes (WGMs). They can confine light inside the cavity, forming WGMs, or focus the light in their proximity, forming PNJs. Both WGMs and PNJs have found numerous applications, including sensing and imaging. In this work, a review of PNJs and their applications in

We put forward a co-axial pump (optical)-probe (x-rays) experimental concept and show performance of the optical component. A Bessel beam generator with a central 100 m diameter hole (on the optical axis) was fabricated using femtosecond (fs) laser structuring inside a silica plate. This flat-axicon optical element produces a needle-like axial intensity distribution which can be used for the optical

We describe the first use of range-resolved interferometric signal processing for measurement of spectral transmission. This was applied to gas sensing using tunable diode laser spectroscopy, allowing the simultaneous and independent measurement of methane concentrations in multiple gas cells. The system uses a single injection-current modulated diode laser and a single photodetector. For three gas

We demonstrate the use of tip-enhanced Raman spectroscopy (TERS) on polymeric microstructures fabricated by two-photon polymerization direct laser writing (TPP-DLW). Compared to the signal intensity obtained in confocal Raman microscopy, a linear enhancement of almost two times is measured when using TERS. Because the probing volume is much smaller in TERS than in confocal Raman microscopy, the effective

If high numerical apertures are used in coherence scanning interferometry, an extension of the interference signal’s spectral distribution to lower frequencies can be observed. Depending on the slope of the measured surface interference signal contributions belonging to higher frequencies will vanish. In addition, the high spatial frequency information of a measured surface structure will contribute

The COVID-19 pandemic has revealed the need of novel diagnostic technologies for rapid and accurate virus detection. In the European CONVAT project, a point-of-care nanophotonic biosensor is being developed for the direct, fast and specific identification of severe acute respiratory syndrome coronavirus 2 from both human patient samples and animal reservoirs. The technology will provide a quantitative

Graphene patterned into plasmonic structures like ribbons or discs strongly increases the linear and nonlinear optical interaction at resonance. The nonlinear optical response is governed by hot carriers, leading to a red-shift of the plasmon frequency. In magnetic fields, the plasmon hybridizes with the cyclotron resonance, resulting in a splitting of the plasmonic absorption into two branches. Here

In this contribution, we investigate second harmonic generation (SHG) in periodically poled lithium niobate (LN) on insulator waveguides and examine under what conditions such waveguides suffer from undesirable loss due to lateral leakage. We investigate the lateral leakage losses in X-cut and Z-cut LN for the fundamental (1550 nm) and second harmonic (775 nm) wavelengths. Our findings show that Z-cut

Although plasmonics and high refractive index photonics have experienced very fast growth thanks to classical physics concepts, there is an increasing interest in harnessing quantum physics concepts for further pushing the frontiers of these fields. In this context, this perspective highlights the importance of some quantum nanostructures for building nanomaterials and metamaterials with enhanced plasmonic

Attosecond interferometry (AI) is an experimental technique based on ionizing a system with an attosecond pulse train in the presence of an assisting laser. This assisting laser pulse provides multiple pathways for the photoelectron wave packet to reach the same final states, and interference of these pathways can be used to probe the properties of matter. The mechanism of AI is well-understood for

Imaging through multimode fibers (MMFs) is a challenging task. Some approaches, e.g. transmission matrix or digital phase conjugation, have been developed to realize imaging through MMF. However, all these approaches seem sensitive to the external environment and the condition of MMF, such as the bent condition and the movement of the MMF. In this paper, we experimentally demonstrate the high-fidelity

The nitrogen vacancy (NV) center in diamond has wide applications in sensing, imaging and quantum information processing. One of the bases of these applications is to localize the NV center in diamond with high precision. In this work we demonstrate a method for nanoscale imaging and locating near-surface NV centers on diamond waveguides based on an atomic force microscopy (AFM) combined confocal system

Coherent beam combining is a method for combining multiple emitters into one high power beam by means of relative phase stabilization. Usually, modulation or interferometric techniques are used to generate an error signal. This is relatively complicated and expensive. Especially in the case of tiled aperture combining the beam profile is usually monitored anyway. This beam profile should contain most

With ever-increasing demand for three-dimensional (3D) imaging and shape measurements in a variety of fields, measurement accuracy has become of vital importance to numerous scientific and engineering applications. This paper presents an experimental investigation into the accuracy comparison of two prevalent 3D imaging and shape measurement methods: fringe projection profilometry (FPP) and 3D digital

Ultrafast high-order mode (HOM) lasers are a relatively new class of ultrafast optics. They play a significant role in the fieldsof scientific research and industrial applications due to the high peak power and unique properties of spatial intensity and polarization distribution. Generation of ultrafast HOM beams in all-fiber systems has become an important research direction. In this paper, all-fiber

Miniature spectrometers provide promising potential for on-chip or in situ optical analysis. In recent years there has been significant progress towards reducing the size and improving the performance of these spectrometers. The workhorse is light splitting components. This work has been led primarily by the innovative use of new light analysis strategies and new nanostructured materials with the notable

Here we develop the first optical neuromorphic processor for frequency-multiplexed and multi-channel signals and demonstrate its application for orthogonal frequency-division multiplexing and wavelength-division multiplexing. The presented architecture supports multichannel operation through incorporation of the optical Fourier transform and dispersion-managed fiber echo state network analogue enabling

Terahertz (THz) in vivo reflection imaging can be used to assess the water content of the surface of the skin. This study presents the results of treating 20 subjects with aqueous, anhydrous and water-oil emulsion samples and observing the changes induced in the skin using THz sensing. These regions were also measured with a corneometer, the present gold standard for skin hydration assessment within

We demonstrate a new technique for filling mm-scale microfabricated silicon and glass cavities with alkali vapors at the wafer-scale. A single etched silicon wafer contains an array of cavities containing alkali precursor materials offset laterally from the cell array. The wafer is heated to create an array of alkali droplets on an upper glass wafer, which is then translated laterally under vacuum

The development of compact and energy-efficient miniaturised lasers is a critical challenge in integrated non-linear photonics. Current research focuses on the integration of subwavelength all-dielectric lasers in CMOS compatible platforms. These systems provide a viable alternative to state-of-the-art nanoplasmonic sources, whose practicality is often hindered by high metal losses. The efficiency

Analysis of surface structures formed due to femtosecond laser surface ablation is usually done through subjective assessment of the surface images. Here, we analyze the evolution of femtosecond laser-induced surface structures using multifractal analysis. We computed the singularity spectrum to characterize the behavior of laser-induced herringbone patterns. The surface morphology of the ablated surface

Brillouin imaging (BI) is increasingly recognized to be a powerful technique that enables non-invasive measurement of the mechanical properties of cells and tissues on a microscopic scale. This provides an unprecedented means for investigating cell mechanobiology, cell-matrix interactions, tissue biomechanics and other fundamental biological questions. Recent advances in optical hardware have accelerated

The past decade has seen significant growth in the field of thin film lithium niobate electro-optic modulators, which promise reduced voltage requirements and higher modulation bandwidths on a potentially integrated platform. This article discusses the state-of-the-art in thin film modulator technology and presents a simplified simulation technique for quickly optimizing a hybrid silicon- or silicon

Acoustic waves in an optical medium cause rapid periodic changes in the refraction index, leading to diffraction effects. Such acoustically controlled diffraction can be used to modulate, deflect, and focus light at microsecond timescales, paving the way for advanced optical microscopy designs that feature unprecedented spatiotemporal resolution. In this article, we review the operational principles

A new intriguing paradigm recently emerged in bio-photonics, in which a single biological element such as a simple cell can be used as an optical or photonic component having well-defined features. Based on this novel concept, the interactions between light and biological matter can be exploited in many circumstances as useful tools in various fields of science and technology. In fact, it is surprising

Imaging with terahertz (THz) waves has been expected as a non-invasive/non-staining visualization tool for breast cancer margins during surgeries. Breast cancer is a generic name for a heterogeneous lesion comprising invasive adenocarcinoma, in situ adenocarcinoma, most frequently in the form of ductal carcinoma in situ (DCIS) and benign tissues. Until now, THz imaging has focused on invasive adenocarcinoma;

Fourier transform profilometry (FTP) is a classic three-dimensional (3D) shape measurement technique that can retrieve the wrapped phase from a single fringe pattern. However, suffering from the spectral leakage and overlapping problems, it generally yields a coarse phase map with low spatial resolution and precision. Recently, deep learning has been introduced to the field of Fringe projection profilometry

Extreme ultraviolet high-harmonic generation (HHG) from bulk liquids has only recently been demonstrated (T.T. Luu, Z. Yin et al , Nat. Comm. 9, 3724, (2018)). This has opened new prospects for the development of bright high-harmonic sources and the development of liquid-phase high-harmonic spectroscopy (HHS). Here, we report on the first observation of HHG in liquids driven by few-cycle (∼7 fs) pulses

We experimentally demonstrate the generation of soliton-like pulses with 195–230 fs duration and energy up to 20 nJ in the spectral region of 1.9–2.5 µ m directly from the Tm-doped all-fiber MOPA laser. The emerged Raman solitons generated directly in the fiber amplifier exhibit unusual dynamics and spectral properties forming a supercontinuum without conventional gaps between Stokes pulses. Namely

We examine the nature of the reconstructed 3D image as obtained by replay (or back-propagation) of the object wave from the hologram recording plane to the original object volume. While recording of a hologram involves transferring information from a 3D volume to a 2D detector, the replay of the hologram involves creating information in a set of 3D voxels from a much smaller number of 2D detector pixels

We achieve record concurrent combinations of bandwidth (18 GHz), optical output power (150 mW), and wall plug efficiency (30%) with a unique arrangement of 19-element, electrically parallel 980 nm vertical cavity surface emitting laser (VCSEL) arrays. We use a new two-dimensional, quasi honeycomb geometry with inter-VCSEL ridge connectors—made nonconducting by selective thermal oxidation—to improve

Optical neuoromorphic technologies enable neural network-based signal processing through a specifically designed hardware and may confer advantages in speed and energy. However, the advances of such technologies in bandwidth and/or dimensionality are often limited by the constraints of the underlying material. Optical fiber presents a well-studied low-cost solution with unique advantages for low-loss

Laser-assisted protein adsorption by photobleaching (LAPAP) is a versatile tool to nanopattern proteins on the micrometer scale. Sub-micron patterning is, however, difficult due to diffraction. We show that, similar to stimulated emission depletion (STED) microscopy, a depleting beam can effectively suppress LAPAP and hence is apt to locally control LAPAP in order to write sub-diffractional lines of

Fluorescence lifetime imaging microscopy (FLIM) is a powerful technique in biomedical research that uses the fluorophore decay rate to provide additional contrast in fluorescence microscopy. However, at present, the calculation, analysis, and interpretation of FLIM is a complex, slow, and computationally expensive process. Machine learning (ML) techniques are well suited to extract and interpret measurements

Dual-comb spectroscopy (DCS) is a promising approach for real time, high precision, and high sensitivity Fourier-transform spectroscopy. DCS requires a pair of tightly phase-locked optical frequency combs (OFCs). The intrinsic complexity hinders practical application of this technique. Recently, there is a new trend of generating a pair of OFCs with slightly different repetition rate from a single

We investigate the minimum acquisition time, expressed as the number of image frames, and the minimum number of absorbed photons per pixel required to achieve a predefined contrast resolution in a monochromatic, pixelated image acquisition system at low light intensities (from well below one photon, to several hundred photons per pixel and frame). Primarily we compare systems based on the pixels of

Broadband lasers oscillating in multiple longitudinal modes have potential applications on high resolution interferometer, optical communication and laser spectroscopy. However, the bandwidth of the laser spectrum is limited by the spectral range of laser materials. Here, a broadband multi-longitudinal-mode laser with bandwidth of 22.4 nm at first-order Stokes wavelength has been achieved in a Yb:YAG/YVO

Brain-inspired computing concepts like artificial neural networks have become promising alternatives to classical von Neumann computer architectures. Photonic neural networks target the realizations of neurons, network connections and potentially learning in photonic substrates. Here, we report the development of a nanophotonic hardware platform of fast and energy-efficient photonic neurons via arrays

Superoscillations are making a growing impact on an ever-increasing number of real-world applications, as early theoretical analysis has evolved into wide experimental realisation. This is particularly true in optics: the first application area to have extensively embraced superoscillations, with much recent growth. This review provides a tool for anyone planning to expand the boundaries in an application

This work reports on an investigation of the optical feedback in an InAs/InGaAs passively mode-locked quantum dot (QD) laser epitaxially grown on silicon. Under the stably-resonant optical feedback condition, experiments demonstrate that the radio-frequency linewidth is narrowed whatever the bias voltage applied on the saturable absorber (SA) is; on the other hand, the effective linewidth enhancement

Many optical systems require the correction of the cumulative wavefront error of the system for performance optimization. In ophthalmology the wavefront error of the eye corresponds to the visual defect and can be measured up to high-order aberrations today. Lower orders of the wavefront error are usually corrected with spectacles, contact lenses or refractive surgery. In this paper we apply an optimization

Recent developments in extreme ultraviolet (XUV) and x-ray radiation sources have pushed pulse energies and durations to unprecedented levels that opened up the era of non-linear XUV and x-ray optics. In this quest, laser driven high order harmonic generation sources providing attosecond resolution in the XUV spectral region enabled XUV-pump-XUV-probe experiments, while Free Electron Laser research

The ongoing growth of use-cases for artificial neural networks (ANNs) fuels the search for new, tailor-made ANN-optimized hardware. Neuromorphic (brain-like) computers are among the proposed highly promising solutions, with optical neuromorphic realizations recently receiving increasing research interest. Among these, photonic neuronal models based on vertical cavity surface emitting lasers (VCSELs)

Surfaces with micro- and nanofeatures were proven to be a superb solution to selectively induce various surface functionalities like anti-bacterial, self- cleaning, friction reduced, hydrophilic or hydrophobic. While there are multiple ways to achieve it, femtosecond (fs) laser-based solutions were shown to offer the best balance between price, throughput and result. Thus, here we will discuss how

All-optical modulation has been regarded as an effective method to solve the electrical bandwidth bottleneck problems existing in the current telecommunication network. By taking advantage of high photothermal conversion of two-dimensional (2D) MXene, a high-performance all-optical modulator is demonstrated. The polarization-dependent all-optical modulator exhibits a broadband intensity modulation

The field of diamond photonics is reviewed, with a focus on recent experimental demonstrations of photonic integrated devices in a single crystal diamond. This field leverages the outstanding material properties of diamond with the aim to establish large-scale integrated photonics for applications in sensing, information and communication technologies, and optomechanics. Accordingly, this review introduces

The debate on tunnelling times have always been full of contradictions and the attoclock experiments that measure tunnelling delays in strong-field ionization are no exception. The current review presents the debate and discussions concerning the studies of tunnelling times based only on the attoclock technique. We review them with their implications and pitfalls identified due to lack of accurate

Optical rogue waves are a class of pulses with extremely large amplitudes, whose probability of occurrence unexpectedly deviates from Gaussian-law statistics. To date, the mechanisms of rogue wave generation are still debated: investigations are under way, exploring the statistics of various pulse dimensions across different physical domains. Although polarization is one of the fundamental parameters